Espresso-type coffee makers are well known. Typically, the espresso-type coffee makers deliver hot water having an optimum temperature of approximately 96 degrees Centigrade through very finely ground coffee in a metallic filter pan using a driving pressure of 3 to 15 bar. Examples of espresso-type coffee makers are described and depicted in U.S. Pat. Nos. 5,280,747; 5,392,694; 4,882,982; and 5,150,645. Current technology in espresso filtration provides for a finely fenestrated metallic filter on top of which are situated coffee grounds, 0.3 millimeters in size or less (particle size). This metallic filter functions to intercept most of the coffee grounds while allowing the liquid coffee beverage along with its oils and some fine particulate grounds to pass into the awaiting cup. Although such filtration of particulate matter (grounds), until presently, has been considered "state of the art" world-wide, recent proof that the lipid fraction (coffee oils) as well as the fine particulate coffee grounds which escape filtration in this previously described system, are indeed harmful to the human organism, has come to light. The compounds cafestol and kahweol, (here "C" and "K") present in the coffee oils in the fine particulate coffee grounds (both which escape metallic filtration; see above) have been extensively studied by medical researchers and have been conclusively shown to substantially elevate serum, cholesterol, triglycerides, and liver function tests. See, for example, P. Zock, M. B. Katan, M. P. Merkus, et al., Effect of a Lipid-Rich Fraction from Boiled Coffee on Serum Cholesterol, Lancet 1990; 335:1235-7; H. Heckers, U. Gobel & U. Kleppel, End of the Coffee Mystery: Diterpene Alcohols Raise Serum Low-Density Lipoprotein Cholesterol and Triglyceride Levels, Journal of Internal Medicine, (J. Int. Med.) 1994; 235:192-3; R. Urgert, A. G. M. Schultz & M. B. Katan, Effects of Cafestol and Kahweol from Coffee Ground Son Serm Lipids and Serum Liver Enzymes in Humans, American Journal of Clinical Nutrition (AM. J. Clin. Nutr.) 1995; 61:149-54; W. Weusten-Van Der Woy, et al., Identity of the Cholesterol--Raising Factor From Boiled Coffee and its Effects on Liver Functions Enzymes, Journal of Lipid Research (J. Lipid. Res.) 1994; 35:721-33; E. Arnesen, N. E. Huseby, T. Brenn & K. Try, The Tromso Heart Study, Distribution of, and Determinants for, Gamma-Glutamyl Transferase in a free Living Population, Scandinavian Journal of Clinical Laboratory Investigation, (Scand. J. Clin. Lab. Invest.) 1986; 46:63-70; O. Nelssen, D. H. Forde, & T. Brenn, The Tromso Study. Distribution and Population Determinates of Gamma-Glutamyl Transferase, American Journal of Epidemiology (AM. J. Epidemiol.) 1990; 132:318-26; Ulmann's Encyclopedia of Industrial Chemistry--5th Edition, 1986; Vol. A7:pg. 334; M. Van Desseldorp, et al., Cholesterol--Raising Factor from Boiled Coffee does not Pass a Paper Filter, Arteriosclerosis and Thrombosis 1991; 11:586-93.
About 18% of Arabic coffee (bean) is lipid (oil). Of that 18%, 20% is composed of fatty acid esters of diterpene alcohols known as cafestol and kahweol (herein "C" and "K"). The aforementioned Zock, et al. article showed that the lipid (oil) rich floating on the surface of boiled coffee raised the serum LDL-C cholesterol and serum triglycerides (both atherogenic) by 29% and 55% respectively. The aforementioned Heckers, et al. article found that subjects given 148 mg of C and K daily for one month had a 50% increase in serum LDL-C and an 87% increase in serum triglycerides. One double espresso (approximately 30 cc) can contain up to 24 mg of C and K in a single cup. [Furthermore, the espresso brewing method was shown by Urgert, et aL in the Journal of Agricultural and Food Chemistry, August 1995 to be the most effective at extracting the harmful compounds C and K, when compared to other brewing methods, i.e. drip vs. boil vs. percolation, etc.]
The previously cited article by Urgert, et al. confirms the above results, but the studies there described are based on the C and K found in the particulate grounds found at the bottom of the coffee cup. The particulate grounds which escaped filtration were found to be potent carriers of C and K and in addition to raising cholesterol and triglycerides C and K were found to elevate liver enzymes serum ALT (alanine aminotransferase) and serum AST (aspartate aminotransferase) to a lesser extent. These liver enzymes, when elevated, can indicate hepatocellular (liver) disfunction and/or damage. Other researchers confirmed the adverse effects of C and K on the liver function tests. See, for example, the aforecited Urgert, et al., Weusten-Van Der Wouw, et al., Amesen, et aL and Nilssen, et aL references.
This assemblage of evidence clearly establishes the need for a filter which can rid an espresso coffee beverage of its harmful oils and unfiltered grounds, which is what the present invention can accomplish.
It has been discovered that paper coffee filters can remove substantially the C and K in coffee beverages by filtering both the oils and small particulate grounds which have been found to house C and K. See the aforecited Urgert, et aL paper and the article by Van Desseldorp, et aL. Prior to the present invention, paper filters have not been developed for espresso-type coffee makers since it would appear to be redundant to the metallic filter.